Tube construction



Get. 13, 1953 J. H. COOPER 2,655,181

TUBE CONSTRUCTION Filed Sept. 14, 1949 INVENTOR.

JAMES H. COOPER BY Z QTTOPNEV v Patented Oct. 13, 1953 TUBE CONSTRUCTIONJames .11. Cooper, Grosse Pointe Park, Mich, as-

signor t McCord Corporation, Detroit, Mich., a

corporation of Maine Application September 14, 1949, Serial No. 115,607

4 Claims. 1'

This invention relates to the heat exchange art and has particularreference to heat exchange devices of the fin and tube type.

More specifically, the invention relates to heat exchange devices of thekind shown in Seemiller Patent No. 2,252,211, issued August 12, 194-1,for Heat Exchange Core, and contemplates a novel construction for thetube of such a device and a novel construction for such a heat exchangedevice employing a single row of such tubes arranged as part of a corewith pleated fins between the tubes and in which the pleats of the finextend crosswise of the tube, and in which the length of the pleats ofthe fin and the width of the tubes are substantially co-extensive.

A principal object of the invention is to provide a novel heat exchangedevice.

A further object of the invention is to provide a novel tube structurewhich is particularly useful in heat exchange devices of the typereferred to.

Another object of the invention is to provide a novel construction forheat exchange cores.

.Other and further objects of the invention will be apparent from thefollowing description and claims and may be understood by reference tothe accompanying drawing, of which there is one sheet, which by way ofillustration shows a preferred embodiment of the invention and what Inow consider to be the best mode in which I have contemplated applyingthe principles of my invention. Other embodiments of the invention maybe used without departing from the scope of the present invention as setforth in the appended claims.

In the drawings:

Fig. 1 is a fragmentary perspective view, with parts broken away, of aheat exchange core embodying the invention;

Fig. 2 is an enlarged and elevational view of I a tube embodying theinvention;

Fig. 3 is an enlarged fragmentary sectional view taken along the line3-3 of Fig 1; and

Fig. 4: is a fragmentary sectional view taken along the line 4-4 of Fig.3.

In Fig. 1 there is shown a fragmentary portion of a heat exchange coreembodying the in vention, such core being particularly useful as aradiator core for the cooling system of an internal combustion engine ofa motor vehicle. Such a core may consist of a series of tubes ii!disposed with the Wide sides thereof parallel to each other and securedat their upper and lower ends in plates, such as the plate 12 whichforms a part of a header with which the tubes H) communicate. A strip Mof pleated fins is arranged between each pair or set of adjacent tubesIll.

The fin strips it may be of the construction shown in Seernlller PatentNo. 2,252,211, and in general are made out of thin metal stock, such ascopper, of the order of .903 inch thickness. The strip t comprises apleated metal strip having all of its folds 16 substantially parallelwith one another, and may have a frequency of the order of ten per inch.The turned over edges N3 of each fold preferably are rounded and ofsubstantial width, and each edge I8 seats against a side of the tube asshown in Figs. 1 and 4, it being noted that the width of the tube It issubstantially co-extensive with the length of the edge [8. As usedherein, the width of the tube has reference to its dimension across thewide sides thereof and between the two faces of the core, the narrowsides of the tubes being disposed in the faces of the core.

The tubes embodying the invention may be made of copper or brass or anyother suitable metal stock of the order of .005 inch and the tubes maybe spaced from each other approximately one-half inch. Each of the tubesit is made from an elongated piece of such thin flexible metal which isformed lengthwise thereof to provide two offset portions 29 connected bya central portion 22 which is disposed transversely of the offsetportions 26. Each of the ofiset portions has the outer part 24 thereofturned back upon itself generally in alignment with that part of theother offset portion 22, adjacent the central portion 22. The ends 26 ofthe turned back parts are bent back upon themselves as indicated at 28and nested in the shoulders 39 formed between the central portion 22 andthe offset portions 20.

The tube may be formed in a tube mill which progressively bends themetal stock to the form shown in Fig. 2. The formed stock is subjectedto a fluxing bath and given a coat of solder in order to coat theoutside of the tubes with a solder coating indicated at 32, such soldercoating flowing into the joints between the bent back parts 26 and thecentral portion 22 so as to unite such parts and form water-tight jointscapable of withstanding the pressures encountered in heat exchange coresof the type in question.

It will be observed that the tube is generally flat in cross section andthat the central portion 22 divides the tube into two passages 34.During the formation of the tube the parts 29 and 24, which define theopposite sides of the passages 34, are outwardly bulged as shown in Fig.2 for a purpose that will hereinafter be pointed out.

The central portion 22 and the portions 26 in contact therewith form astiffening means for the tube so as to resist collapsing of the sidesthereof. In addition such portions 22 and 26 also serve as a path forthe flow of heat between the liquid in the center of passages 34 and theouter side surfaces of the tube.

In assembling the radiator core the tubes i9 and the fins 14 are stackedwith the tubes and fins alternately arranged until a core of the desireddimension is obtained. The assembly is then compressed by pressing thetubes toward each other so as to obtain a good metallic contact 3between the edges l8 of the fins and the outside walls of the tubes 10.The outwardly bulged sides of the tubes make it possible to obtainuniformly good contact between the edges 18 of each of the fins and theside walls of the. tubes,

and after the stack of tubes and fins is compressed the outwardly bulgedsides of the tubes are compressed inwardly so that the contact betweeneach edge 18 of a fin and the side wall of the tube is in asubstantially straight line,- asshown in Fig. 3.

After the plates 12 which form part of the headers, are assembled onboth ends of the tubes as shown in Fig- 1,.the assembly may be runthrough a baking furnace so. that the solder coating 32 on the outsideof the tubes'will melt and form a good heat transfer joint between thefins l4 and the tubes [0 which integrally unites the tubes and the fins.During this baking operation the solder also flows. into the jointbetween the. bent back parts 26 andv the, central portion 22 so as toform a good pressure tight joint therebetween.

In use, air flows over the tubes [0 and between the folds or pleats l6of the fins I4, the fins forming secondary surfaces for the liquidcontained in the tubes Ill. The thickness of the solder coating 32 issomewhat exaggerated for illustrative purposes.

By using a single tube of the construction shown, it is possible toobtain contact between the entire length of each fin edge 18 and a tube[0. This makes it possible to reduce the thickness of the core.

The stiffening means incorporated in the tube and formed by the centralportion 22 and the bent back portions 26 also function as fin spacers inthat they accurately space each fin it from the next fin and prevent thecollapse of the tube under the pressure to which the fins and tubes aresubjected in the assembly operation.

The heat exchange core embodying the invention thus comprises a seriesof thin. fiat tubes of metallic material disposed with the wide sidesthereof parallel to each other and with a flexible corrugated fin 14arranged between and spacing the wide sides of each set of adjacenttubes 10.. The folds iii of each of said corrugated. fins extendcrosswise of the tubes and between the front and rear faces of the core.The narrow sides of each of the tubes are arranged in the core faces.

Due to the pressure under which the fins and tubes are pressed togetherduring the assembly operation, each fin has theedges of its folds incontinuous,v resilient contact with the wide sides of an adjacent set oftubesthroughout substann tially the entire extent of the length of suchedges t8 and the-width of the tubes M1,, and each of the tubes hasintegral stiffeningmeans intermediate the narrow sides thereof andextending length wise of the tubes; such stiffening means resistingcollapse of the wide-sidesof the tubes and forming a means for spacingadjacentfins from each other. Such stiffening means also forms ametallic: path for the flow of heat directly from the center of: thetubestothe outside thereof and to the fins 14. Some of the. resiliencyor flexibility of the stock. will be. lost during thebaking operation.

The acute angle corner formed between the central portion 22 and each ofthe offset portions 20 and the nesting of'the bent back ends 26 in suchcorners provides a mechanical interlocking of' the parts of the tubejoints which help to 4 locate the parts of the joint rat the, solderingoperation and also provide a stronger joint.

For some applications the fins may project slightly beyond the tubes inorder to protect the latter. The term solder as used herein includes acoating on the tube [0 suitable for brazin operations so that. the tubejoints may be brazed, as wellas the. tubing brazed to the fin edges.

The heat exchanger illustrated has particular reference to radiator coreconstruction. For other types of heat exchangers, other metals such assteel may be empolyed, and the metal gauge may be lighter or heavierthan that specified, depend ing on the particular requirements of eachapplication.

While I have illustrated and described apreferred embodiment of myinvention, it is understood that this is capable of modification and 1therefore do not wish to be limited to the precise details set, forthbut desire to avail myself bf such changes and alterations as fallwithin the purview of the following claims.

I claim:

1. A tube useful for heat exchange purposes comprising an elongatedpiece of thin flexible metal formed lengthwise thereof to provide twosubstantially flat offset side portions connected by a centraltransversely extending portion with a shoulder between said centralportionand each of said oiiset portions, each of said offset sideportions having the outer part thereof turned back upon itself generallyin alignment with that part of the other ofiset portion adjacent saidcentral portion to form other side portions, the ends of said turnedback parts being bent inwardly back upon themselves toform portionsparallel to and seated against said central por ticn and extending intosaid corners, and means integrally uniting said parallel portions of"said bent back ends to said central portion so as to form a pressuretight tube,- said central portion and bent back portions integrallyunited there-- with extending transversely of said tube length.- wisethereof fromone side to the other thereor and forming a multiplystiffening element which extends between and supports.- the sides ofsaid tube intermediate the ends thereof- 2. A tube according to claim 1wherein said ends of said turned back parts are. bent toform cornerportions in addition to said parallel portions and wherein said cornerportions are -nest-' ed in said corners.

3. A tube according to claim 1 wherein said central portion divides saidtube into two passages and wherein the portions of said piece formingthe opposite sides of said passages are outwardly bulged.

4. A tube according to claim 1 wherein said central portion forms anacute angle corner with each of said offset portions.

JAMES H. COOPER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,104,714 Sonnier July 21, 1914 1,522,404 Albach Jan. 6, 19251,899,417 Higgins Feb. 28, 1933 2,252,210 Seemiller Aug. 12, 19412,554,185 Giegerich May 22, 1951 FOREIGN PATENTS Number Country Date337,463 Germany June 1, 1921 662,327 Germany Nov. 9, 1938

